The PCB industry considers an RF circuit board to include any PCB that operates at a “high” frequency, e.g. a radio frequency. A subclass of RF circuit boards are microwave PCBs, i.e. any PCB that operates at a frequency 20 KHz to 300 GHz.
RF boards have a wide number of applications or use-cases, such as, but not limited to, wireless systems such as Wi-Fi-routers and other wireless local area networking technologies, smart phones or cellular phones, sensors, robots and security systems. RF board manufacturers include Apple, Samsung, Nokia, Agilent, and analog devices. RF boards often, but not necessarily, have transmitter/receiver functionality. RF boards (or RF cards), when empty, may be termed RF PCBs, and, once assembled, may be termed RF PCB assemblies, or RF modules.
Wikipedia indicates that “MMCX (micro-miniature coaxial) connectors are coaxial RF connectors similar to MCX, but smaller, conforming to the European CECC 22000 specification.
The connectors have a lock-snap mechanism allowing 360-degree rotation and usually have a 50Ω impedance. They offer broadband capability from DC to 6 GHz. MMCX connectors are most commonly seen on Wi-Fi PCMCIA cards as antenna connectors or as connectors for external GPS antennas on small devices like PDAS or GPS receivers. They are also used by various brands of in-ear monitors to connect the cable to the individual earpieces. This allows for the cables to be replaced or swapped. MMCX is also used in some video transmitters for first-person view (FPV) radio control piloting. This makes swapping antennas and repairing easier than with U.FL connectors.
Wikipedia teaches that a ground (GND) plane on a printed circuit board (PCB) may comprise an area or layer of copper foil connected to the circuit's ground point, usually one terminal of the power supply which may serve as the return path for current from various components. A ground plane often covers most of the PCB area not occupied by circuit traces. In multilayer PCBs, the ground plane may be a separate layer covering the entire board. The ground plane, due to its size, typically ensures that the components' respective ground connection are all at the same reference potential since it conducts large return currents from many components without significant voltage drops. In radio frequency PCBs, ground planes may reduce electrical noise and interference through ground loops and/or prevent crosstalk between adjacent circuit traces. When digital circuits switch state, large current pulses flow from the active devices (transistors or integrated circuits) through the ground circuit. If the power supply and ground traces have large impedance, the voltage drop across them may create noise voltage pulses that disturb other parts of the circuit (ground bounce). Since the conducting area of the ground plane has, due to its large size, far lower impedance than that in a circuit trace, current pulses cause less disturbance when a ground plane is provided. A ground plane under printed circuit traces may reduce crosstalk between adjacent traces. In crosstalk, an electrical signal in one trace is coupled into another adjacent parallel trace through electromagnetic induction by magnetic field lines from one trace linking the other. However, if a ground plane layer is underneath, the ground plane forms a transmission line with the trace in which case the oppositely-directed return currents flow through the ground plane directly beneath the trace, thereby to reduce crosstalk by confining most of the electromagnetic fields to the area near the trace. A power plane may be used in addition to a ground plane in a multilayer circuit board, to distribute DC power to the active devices. The two facing areas of copper create a large parallel plate decoupling capacitor that prevents noise from being coupled from one circuit to another through the power supply. Ground planes may be split into plural planes respectively connected by a thin trace to allow separation of analog and digital sections of a board or inputs and outputs of amplifiers. The trace is typically thin enough to provide impedance low enough to keep the two ground planes close to the same potential while preventing the ground currents of one side from coupling into the other side, causing ground loop.
Wikipedia states that “surface-mount technology (SMT) is a method for producing electronic circuits in which the components are mounted or placed directly onto the surface of printed circuit boards (PCBs). An electronic device so made is called a surface-mount device (SMD). In industry it has largely replaced the through-hole technology construction method of fitting components with wire leads into holes in the circuit board. Both technologies can be used on the same board, with the through-hole technology used for components not suitable for surface mounting such as large transformers and heat-sinked power semiconductors.”
Each component on a printed circuit board (PCB), whether SMT or through hole, has a footprint or land pattern on the PCB. SMT footprints are differentiable from through hole footprints; an SMT footprint of a specific SMT component comprises surface-mount technology pads in the PCB, typically in the component/solder side (CS/SS) layer thereof, whose arrangement matches the arrangement of leads on the specific SMT component and which are later used to both mechanically attach and electrically connect that specific SMT component to the printed circuit board.
A through-hole footprint of a specific through-hole component comprises through-holes provided in the PCB whose arrangement matches the arrangement of leads on the specific through-hole component. These through-holes are later used to both mechanically attach and electrically connect that specific through-hole component to the printed circuit board.
Typically, but not necessarily, the footprint of each component is designated e.g. in white, in a silkscreen layer, in which, typically, material is deposited in certain locations to be indicated (e.g. a footprint), and not in other areas. Even in the absence of a silkscreen layer e.g. in PCBs whose “real estate” is very dense, such as those in state of the art cellphones, the footprints' locations are known from the PCB's documentation e.g. assembly drawings.
US2011094787 A1 describes a printed circuit board which includes a layer. A layer of copper is covered on a surface of the layer. A through-hole passes through the printed circuit board. A number of thermal engravings are defined in the layer around the through-hole. Each thermal engraving is a groove defined in the surface of the layer, without being covered with the layer of copper. The number of thermal engravings are not in contact with each other. The printed circuit board (PCB) includes a ground layer and other layers such as signal layers. The PCB defines a through-hole through the ground layer and the other layers. A layer of copper is arranged on a surface of the ground layer. The ground layer defines four thermal engravings. A component may be mounted on the PCB by inserting a lead of the component through the through-hole and then soldering the lead in place on an opposite side of the printed circuit board. The lead of the component is electrically connected to the ground layer and other layers, to transmit signals between layers of the PCB and the component. As a result, when the lead of the component is inserted through the through-hole, heat dissipation is slower because of relatively less copper in the area of the through-hole due to the existence of the thermal engravings. The temperature in the through-hole of the PCB is higher than in the through-hole of the conventional PCB during soldering, and the thicker the ground layer, the greater the difference in temperature. The higher temperature is indicative of the slower heat dissipation in the area of the through-hole during soldering, meaning fault formation is decreased or even eliminated.
U.S. Pat. No. 8,350,157 describes a printed circuit board. A layer of copper is covered on a surface of the layer. A through-hole passes through the printed circuit board. An approximately C-shaped thermal engraving is defined in the surface of the layers, surrounding the through-hole and without being covered by the layer of copper. An opening of the thermal engraving faces an output terminal of the power supply. The printed circuit board (PCB) includes a power supply, a power layer and other layers such as a ground layer and signal layers. The PCB defines a through-hole through the power layer and the other layers. A layer of copper is arranged on a surface of the power layer. The power layer defines a thermal engraving. The temperature in the through-hole of the PCB is higher than in the through-hole of the conventional PCB during soldering, and the thicker the ground layer, the greater the difference in temperature. The higher temperature is indicative of the slower heat dissipation in the area of the through-hole during soldering, meaning fault formation is decreased or even eliminated. In other embodiments, thermal engraving is arranged in another layer, say a ground layer of the PCB. In addition, a shape of the groove of the thermal engraving may be changed.
U.S. Pat. No. 6,853,091 describes a printed circuit board and soldering structure for soldering electronic parts thereto. A printed circuit board having circuit patterns printed thereon has a plurality of composite lands each including a first land having a terminal hole formed at its center for inserting the terminal of a selected electric or electronic part or device, and a plurality of second lands each being contiguous to and extending outwards from the first land. The areas contiguous to the contours of the first and second lands have no conductive foils, such as copper foils, thereon, such that the substrate surface of the printed circuit board is exposed in these areas. The exposed areas effectively confine the thermal energy in the limited areas for soldering. Additionally, the composite land shape defines a ridged cone-like solder lump, which can fixedly grip the terminal of the part or device.
U.S. Pat. No. 7,759,604 describes a method for high-precision fixing of a miniaturized component on a support plate. The miniaturized component may have a micro-optical element, on a predetermined fixing section of a support plate by a solder joint. The support plate is formed throughout from a metallic material and has a cut-out region which encloses the fixing section, is bridged by at least one connecting web of the support plate, keeps the heat transfer from the fixing section to the remaining support plate low and compensates lateral thermal expansions of the fixing section. Solder material) is applied on the top of the fixing section. The method comprises in particular the steps: arrangement of the component above the fixing section, the solder material and the base of the component being present in opposite positions without contact and forming a space; supply of electromagnetic radiation to the bottom of the fixing section for melting the solder material so that, as a result of drop formation and optionally as a result of lowering of the component the space fills with molten solder material for mutual fixing.
U.S. Pat. No. 5,473,813 describes methods of forming electronic multi-layer printed circuit boards and/or cards and electronic packages including said boards or cards. The method includes the step of forming a plurality of conductive planes. The conductive planes include ground, signal, or power planes. At least one through-hole is formed through at least one of the conductive planes. An electrically conductive material is deposited onto an inside surface of the at least one through-hole to form a plated through-hole. At least one thermal relief passage is formed at least in the at least one of the conductive planes for preventing the diffusion of heat throughout the circuit board or card during the securing or removal of chips or other components to the circuit board or card by heating the material deposited in the at least one through-hole to a temperature above its melting point. The at least one thermal relief passage is located in the vicinity of the at least one through-hole and is free from electrical connection therewith. An electrically insulating material is deposited on at least one side of each of the conductive planes. The planes are placed on top of each other such that a layer of electrically insulating material is located between each of the conductive planes. The conductive planes are joined together to form the multi-layer circuit board or card.
The adafruit.com blog posted the following at the following www location: https://blog.adafruit.com/2012/01/24/eagle-quicktip-thermal-relief-for-those-gnd-pins/: “Have you ever had a pin on a 0.1″ header that you just couldn't get to reflow properly, especially with lead free solder (which requires a higher temperature to work with)? If so, it was almost certainly a GND pin connected to a large GND plane. The problem is that the GND plane dissipates a lot of the heat from the soldering iron. You can try using a much larger tip (larger tips do a better job of conducting heat that small ones), and/or you may need to jack the heat up quite a bit, but sometimes it just won't reflow well to form a solid joint. The solution is easy, but you need to keep the problem in mind when designing the PCB. What you need to add on any GND pin connected to a GND plane (a large area of copper connected to GND) is to restrict the connection to GND to a single bridge, limiting the other areas with layers 41 (tRestrict) or 42 (bRestrict). Just select the rectangle tool and draw a small rectangle beside the pad over 3 of the four bridges, and you should have a MUCH easier time soldering those pins on after the fact. This can also be a good idea with certain large surface-mount parts.”
Acronyms include:
RF: radio frequency
PCB: printed circuit board
SMT: surface mount technology
GND: ground
The disclosures of all publications and patent documents mentioned in the specification, and of the publications and patent documents cited therein directly or indirectly, are hereby incorporated by reference. Materiality of such publications and patent documents to patentability is not conceded.